Dose-guided patient positioning in proton radiotherapy using multicriteria-optimization

Kurz, Christopher; Süss, Philipp; Arnsmeyer, Carolin; Haehnle, Jonas; Teichert, Katrin; Landry, Guillaume; Hofmaier, Jan; Exner, Florian; Hille, Lucas; Kamp, Florian; Thieke, Christian; Ganswindt, Ute; Valentini, Chiara; Hölscher, Tobias; Troost, Esther G.C.; Krause, Mechthild; Belka, Claus; Küfer, Karl‐Heinz; Parodi, Katia; Richter, Christian

doi:10.1016/j.zemedi.2018.10.003

Cited by 13 publications

(12 citation statements)

References 41 publications

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“…Future developments may help to decrease dosimetric deviations of prostate radiation treatments from treatment plans by optimizing repositioning: the advent of MR-linac and the opportunity for real-time MR-guided prostate tracking before and during each treatment fraction may enable adjustments of patient positions based on superior soft tissue contrast and may also help to minimize not only interfractional but also intrafractional motion (32, 33). Additionally, repositioning strategies have been proposed that utilize accumulated dosimetric information over the course of treatment for dose-guided patient repositioning (34). However, in our dataset, dosimetric deviations in all tested dose-volume parameters from the treatment plan were non-significant when daily 3D imaging was performed, making potential further benefits for the treated patients debatable.…”

Section: Discussionmentioning

confidence: 99%

Dosimetric Impact of Interfractional Variations in Prostate Cancer Radiotherapy—Implications for Imaging Frequency and Treatment Adaptation

et al. 2019

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Background and purpose: To analyze deviations of the applied from the planned doses on a voxel-by-voxel basis for definitive prostate cancer radiotherapy depending on anatomic variations and imaging frequency.Materials and methods: Daily in-room CT imaging was performed in treatment position for 10 patients with prostate cancer undergoing intensity-modulated radiotherapy (340 fraction CTs). Applied fraction doses were recalculated on daily images, and voxel-wise dose accumulation was performed using a deformable registration algorithm. For weekly imaging, weekly position correction vectors were derived and used to rigidly register daily scans of that week to the planning CT scan prior to dose accumulation. Applied and prescribed doses were compared in dependence of the imaging frequency, and derived TCP and NTCP values were calculated.Results: Daily CT-based repositioning resulted in non-significant deviations of all analyzed dose-volume, conformity and uniformity parameters to the CTV, bladder and rectum irrespective of anatomic changes. Derived average TCP values were comparable, and NTCP values for the applied doses to the bladder and rectum did not significantly deviate from the planned values. For weekly imaging, the applied D2 to the CTV, rectum and bladder significantly varied from the planned doses, and the CTV conformity index and D98 decreased. While TCP values were comparable, the NTCP for the bladder erroneously appeared reduced for weekly repositioning.Conclusions: Based on daily diagnostic quality CT imaging and voxel-wise dose accumulation, we demonstrated for the first time that daily, but not weekly imaging resulted in only negligible deviations of the applied from the planned doses for prostate intensity-modulated radiotherapy. Therefore, weekly imaging may not be adequately reliable for adaptive treatment delivery techniques for prostate. This work will contribute to devising adaptive re-planning strategies for prostate radiotherapy.

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Section: Discussionmentioning

confidence: 99%

Dosimetric Impact of Interfractional Variations in Prostate Cancer Radiotherapy—Implications for Imaging Frequency and Treatment Adaptation

et al. 2019

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“…The advent of hybrid MR-linear accelerators may further reduce anatomic and dosimetric deviations during the course of hypofractionated prostate radiotherapy, e.g., by utilizing the superior soft tissue contrast and the possibility for real-time prostate tracking: MR-guided imaging concepts would thereby allow to compensate for both interfractional and intrafractional motion ( 39 , 40 ). In contrast to focusing on the dosimetric consequences of underlying anatomic pelvic alterations, novel position correction strategies have been proposed that guide repositioning based on the accumulated doses during treatment ( 41 ). The availability of voxel-wise information regarding accumulated doses in our dataset may help to further devise dose-directed repositioning strategies to compensate for already accumulated deviations during the course of radiotherapy.…”

Section: Discussionmentioning

confidence: 99%

Dosimetric Impact of the Positional Imaging Frequency for Hypofractionated Prostate Radiotherapy – A Voxel-by-Voxel Analysis

et al. 2020

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Background To investigate deviations between planned and applied treatment doses for hypofractionated prostate radiotherapy and to quantify dosimetric accuracy in dependence of the image guidance frequency. Methods Daily diagnostic in-room CTs were carried out in 10 patients in treatment position as image guidance for hypofractionated prostate radiotherapy. Fraction doses were mapped to the planning CTs and recalculated, and applied doses were accumulated voxel-wise using deformable registration. Non-daily imaging schedules were simulated by deriving position correction vectors from individual scans and used to rigidly register the following scans until the next repositioning before dose recalculation and accumulation. Planned and applied doses were compared regarding dose-volume indices and TCP and NTCP values in dependence of the imaging and repositioning frequency. Results Daily image-guided repositioning was associated with only negligible deviations of analyzed dose-volume parameters and conformity/homogeneity indices for the prostate, bladder and rectum. Average CTV T did not significantly deviate from the plan values, and rectum NTCPs were highly comparable, while bladder NTCPs were reduced. For non-daily image-guided repositioning, there were significant deviations in the high-dose range from the planned values. Similarly, CTV dose conformity and homogeneity were reduced. While TCPs and rectal NTCPs did not significantly deteriorate for non-daily repositioning, bladder NTCPs appeared falsely diminished in dependence of the imaging frequency. Conclusion Using voxel-by-voxel dose accumulation, we showed for the first time that daily image-guided repositioning resulted in only negligible dosimetric deviations for hypofractionated prostate radiotherapy. Regarding dosimetric aberrations for non-daily imaging, daily imaging is required to adequately deliver treatment.

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“…MR-guided radiotherapy enables real-time tracking of pelvic organs and may hence contribute to minimizing inter- and intrafractional dosimetric deviations (38–40). Also, mathematical concepts have been proposed that guide daily patient positioning based on the already accumulated doses for each treatment day (41). Based on superior imaging modalities like in-room CT or in-room MRI, adaptive treatment strategies may help to provide a daily treatment plan based on the current anatomy.…”

Section: Discussionmentioning

confidence: 99%

Dosimetric Impact of Interfractional Variations for Post-prostatectomy Radiotherapy to the Prostatic Fossa—Relevance for the Frequency of Position Verification Imaging and Treatment Adaptation

et al. 2019

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Background and purpose: To analyze divergences between the planned and applied treatment doses for post-prostatectomy radiotherapy to the prostatic fossa on a voxel-by-voxel basis based on interfractional anatomic variations and imaging frequency.Materials and methods: For 10 patients receiving intensity-modulated postoperative radiotherapy to the prostatic fossa, position verification was carried out by daily in-room CT imaging in treatment position (340 fraction CTs). Applied fraction doses were recalculated on daily CT scans, and treatment doses were accumulated on a voxel-by-voxel basis after deformable image registration. To simulate weekly imaging, derived weekly position correction vectors were used to rigidly register all daily scans of the respective treatment week onto the planning CT before dose accumulation. Detailed dose statistics of the prescribed and applied treatment doses were compared in relation to the frequency of position verification imaging. Derived NTCP and Pinjury values were calculated for the rectum and bladder.Results: Despite a large variability in the pelvic anatomy, daily CT-based patient repositioning resulted in largely negligible deviations of the analyzed dose-volume, conformity, and uniformity parameters from the planned doses for post-prostatectomy radiotherapy, and only the bladder exhibited significant increases in the accumulated mean and median doses. Derived NTCP for the applied doses to the rectum and bladder and Pinjury values did not significantly deviate from the treatment plan. In contrast, weekly CT-based repositioning resulted in significant decreases of the PTV coverage and dose conformity as well as large deviations of the applied doses to the rectum and bladder from the planned doses. Consecutively, NTCP for the rectum and Pinjury were found falsely reduced for weekly patient repositioning.Conclusions: Our data indicate for the first time in a voxel-by-voxel analysis that daily imaging is required for reliable adaptive delivery of intensity-modulated radiotherapy to the prostatic fossa. This work will help guiding adaptive treatment strategies for post-prostatectomy radiotherapy.

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Dose-guided patient positioning in proton radiotherapy using multicriteria-optimization

Cited by 13 publications

References 41 publications

Dosimetric Impact of Interfractional Variations in Prostate Cancer Radiotherapy—Implications for Imaging Frequency and Treatment Adaptation

Dosimetric Impact of Interfractional Variations in Prostate Cancer Radiotherapy—Implications for Imaging Frequency and Treatment Adaptation

Dosimetric Impact of the Positional Imaging Frequency for Hypofractionated Prostate Radiotherapy – A Voxel-by-Voxel Analysis

Dosimetric Impact of Interfractional Variations for Post-prostatectomy Radiotherapy to the Prostatic Fossa—Relevance for the Frequency of Position Verification Imaging and Treatment Adaptation

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